Pathology of Restrictive Lung Disease Flashcards
What is the interstitium?
The connective tissue space around the airways and vessels and the space between the basement membranes of the alveolar walls
What are the two basement membranes in the alveoli?
Alveolar epithelial (pneumocyte)
Interstitial capillary endothelial cell
Describe the relationship between the two basement membranes in the alveoli.
Usually in direct contact
What is found in the usual interstitium?
Elastic fibres and the occasional cell, like a fibroblast
Discuss the pathology of the interstitium in lung disease.
It becomes thickened due to a space between the two basement membranes
Why is the thickening of the interstitium an issue?
Makes it more difficult for the diffusion of gases.
What happens to the lungs due to the inflammatory process due to the thickening of the interstitium?
They become rigid and stiff
What happens to FEV1 and FVC and the ratio between the two when the elastic tissue in the lungs loses it’s elasticity?
Low FEV1 & Low FVC but FEV1/FVC normal ratio
What may happen to perfusion/ventilation when the small airways are affected by pathology?
There is an imbalance between perfusion and ventilation
Describe what a patient may present with if they have a restrictive lung disease.
Dyspnoea- SOB on exertion (would have to abnormal for that person).
As the disease progresses, what may happen to the symptoms of a patient w restrictive lung disease?
SOB on exertion will g to SOB at rest
What may patients with restrictive lung disease develop?
Type 1 respiratory failure
Heart failure
What is the difference between type 1 and 2 respiratory failure?
Type 1 respiratory failure- the respiratory system cannot adequately provide oxygen to the body.
Type 2 respiratory failure-respiratory system cannot sufficiently remove carbon dioxide from the body.
What can type 1 respiratory failure lead to?
Hypoxemia
What can type 2 respiratory failure lead to?
Hypercapnia -> too much CO2 in the bloodstream
What does a CXR of someone with interstitial lung disease show?
Reduced lung volumes and increased lung markings
What can a chronic inflammatory response involve the formation of?
Granulomas
What can diffuse alveolar damage be associated with?
-Major trauma
-Chemical injury / toxic inhalation
-Circulatory shock
-Drugs
-Infection incl viruses
-Auto(immune) disease
-Radiation
Name some of the viruses which can cause death due to DADS (diffuse alveolar damage syndrome).
Influenza
SARS Cov1 aka covid
SARS Cov2 aka covid
What are most people with DADS going to end up with?
Type 1 respiratory failure- often life threatening
What happens to cells in DADS to try and attempt to repair the fluid filled alveoli?
Proliferation of type 2 pneumocytes
Proliferation of fibroblasts
What happens to the lungs as result of DADS?
Scarred, solid lungs
Name two types of chronic granulomatous response.
Sarcoidosis
Hypersensitivity pneumonitis
What is sarcoidosis?
A multisystem granulomatous disorder
What causes sarcoidosis?
Uknown
Which parts of the body are very likely to be affected by sarcoidosis?
Lymph nodes
Lungs
How may sarcoidosis present in young adults?
Acute arthralgia- joint pain
Erythema nodosum-swollen fat under skin causing bumps
Bilateral hilar lymphadenopathy
How else can sarcoidosis, and a number of other respiratory conditions, be diagnosed?
Accidently on a CXR
Define non-caseating
No necrosis in the middle of a granuloma
What might you see in lymph node sarcoidosis?
Non-caseating epithelioid granulomas
Name some of the antigens which may trigger hypersensitive pneumonitis.
Thermophilic actinomycetes- mould grown on hay
Bird / Animal proteins
Fungi
Chemicals
Others
Describe some of the presenting symptoms in those with hypersensitive pneumonitis.
Fever, dry cough, myalgia,
Chills 4-9 hours after Ag exposure
What might you hear upon auscultation of someone with hypersensitivity pneumonitis?
Crackles, tachyopnoea, wheeze
tachyopnoea= rapid and shallow breathing btw, need to try and remember this
Describe the chronic presentation of hypersensitive pneumonitis.
Insidious- slowly, no symptoms at first
Malaise, SOB, cough
Which two hypersensitivity reactions are there in hypersensitivity pneumonitis?
Type III and Type IV
What forms in type IV hypersensitivity reactions?
Granulomas
Which cells are involved in type III hypersensitivity reactions?
Lymphocytes
Which part of the lungs does hypersensitivity pneumonitis usually affect?
Upper zone of the lung
When might you see someone develop UIP (Usual Interstitial Pneumonitis)?
-If they have a connective tissue disease
-Drug reaction
-Post infection
-Industrial exposure e.g. asbestos
What type of hypersensitivity reaction is associated with UIP?
Type II
What is UIP defined by?
Patchy interstitial chronic inflammation
Smooth muscle and vascular proliferation
Proliferating Fibroblastic Foci
-?don’t really need to be concerned about this, more worried about the concept of UIP as a whole
List some of the presenting symptoms of Idiopathic Pulmonary Fibrosis (UIP).
Dyspnoea, Cough, Basal Crackles, Cyanosis, Clubbing
Is UIP progressive or treatable?
Progressive
Most die within five years
What does the term honeycombing refer to?
Fibrosis or End-Stage Honeycomb Lung
i.e. non functional, shrunken, hardened lung
Just for a recap question to finish- describe what happens in shunt.
Blood passes from the right to left side of the heart without contacting ventilated alveoli
